RADIOGRAPHIC DETERMINATION OF GASTRIC EMPTYING AND GASTROINTESTINAL TRANSIT TIME IN COWNOSE RAYS ( RHINOPTERA BONASUS ) AND WHITESPOTTED BAMBOO SHARKS ( CHILOSCYLLIUM PLAGIOSUM ) AND THE EFFECT OF METOCLOPRAMIDE ON GASTROINTESTINAL MOTILITY.

Gastrointestinal (GI) pathology is common in elasmobranchs; however, information regarding normal GI transit time and the effect of therapeutics on GI motility is lacking. The objective of this study was to determine baseline gastric emptying and GI transit times in cownose rays (Rhinoptera bonasus) and whitespotted bamboo sharks (Chiloscyllium plagiosum) via radiographic barium sulfate contrast studies. Additionally, a pilot study was undertaken to determine the effect of metoclopramide on GI transit time in whitespotted bamboo sharks. Eight cownose rays and eight whitespotted bamboo sharks were administered a 98% w/w barium sulfate suspension at 8 ml/kg via orogastric tube. Post-contrast radiographs were obtained at 2 min, 3, 6, 12, and 23 hr for rays; and 2 min, 3, 6, 9, 12, 16, 25, 30, 36, and every 12 hr until complete gastric emptying occurred for sharks. In cownose rays, the mean and standard error were established for time of initial spiral colon filling (3.4 +/- 0.4 hr), complete spiral colon opacification (12 +/- 0 hr), initial spiral colon emptying (21.6 +/- 1.4 hr), and complete gastric emptying (23 +/- 0 hr). In bamboo sharks, the mean and standard error were established for time of initial spiral colon filling (5.3 +/- 0.5 hr), complete spiral colon opacification (12.4 +/- 1.3 hr), initial spiral colon emptying (22.5 +/- 2.7 hr), and complete gastric emptying (39.9 +/- 3.3 hr). Cownose rays had a significantly shorter time to spiral colon filling and complete gastric emptying compared with bamboo sharks (P < 0.05). Whitespotted bamboo sharks (n = 8) were administered metoclopramide (0.4 mg/kg orally once daily for 10 days) and the barium series was repeated. Complete gastric emptying time was significantly shorter in treated sharks compared with control (P < 0.05), suggesting that metoclopramide may be a useful therapeutic for GI motility disorders in elasmobranchs.